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    <meta charset="UTF-8">
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    <title>Document</title>
</head>
<body>
    <div class="the_div">
    <p>我是p标签</p>
    <h3>我是h3</h3>
    <h3>我是h3</h3>
    <h3>我是h3</h3>
    <a id="theA" href="#">我是一个a标签</a>
    <ul>
        <li>北京</li>
        <li class="fw">天津</li>
        <li>南京</li>
    </ul>
    <ol class="my_li">
        <li>大张</li>
        <li>大王</li>
        <li>大狗</li>
    </ol>
    <ul class="my_li">
        <li>小明</li>
        <li>小红</li>
        <li>小蓝</li>
    </ul>
</div>
<script>
    const theA = document.querySelector('#theA')
    console.log(theA)
    const h3 = document.querySelectorAll('h3')
    console.log(h3)
    const li = document.querySelectorAll('li')
    console.log(li)
    const my = document.querySelectorAll('ul.my_li  li')
    console.log(my)
    const ml = document.querySelector('ul.my_li  li:nth-child(2)')
    ml.innerHTML= '老六'
    ml.style.color = 'red'
    console.log(ml)
    const fw = document.querySelector('.fw')
    fw.style.backgroundColor = '#087'

</script>
</body>
</html>